The reliability of electronic equipment has always been associated with the operating temperatures of its components. In general, the higher the temperature the less reliable the component. For many components, temperatures above fairly well established ranges can be disastrous.
With modern integrated circuits and printed wiring board circuit packs, component density has again reached the point where additional cooling is required.
Many cooling schemes already exist, left over from the days of vacuum tubes and discrete transistors (see, e.g., U.S. Pat. Nos. 3,626,251 issued to Vigue, and 2,445,582 issued to Melville). Some of these require expensive refrigerating equipment and/or extensive space taken from the printed wiring boards. Some of the more recent proposals require separate plenums mounted above the components on printed circuit boards (see, e.g., U.S. Pat. Nos. 4,851,965 issued to Gabuzda, 4,277,816 issued to Dunn et al, 4,674,004 issued to Smith et al, and 4,498,118 issued to Bell). At least one recent proposal has shown the possibility of directing coolant through a hole in a board toward the bottom surface of a component (see U.S. Pat. No. 4,399,484 issued to Mayer).
An object of this invention is to provide a cooling system for electronic circuit packs that is simple, relatively inexpensive, and uses almost no space on the circuit board.